Fluid-break circuit interrupter



July 4, 1933. w. K. RANKIN FLUID BREAK CIRCUIT INTERBUPTER Filed July 9, 1950 inventer:

William K. Fe'mhhw, r, adv

His Attornej,

PL2. l.

Patented July 4,Y 1933 UNITED STATES PATENT ori-ICE WILLIAM K. RANIKIN, OF LANSDOWNE, PENNSYLVANIA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK FLUID-BREAK CIRCUIT INTERRUPTER Application led July 9,

My invention relates to duid-breaker circuit interrupters and more particularly to` interrupters of the lexpulsion or so-called explosion chamber type wherein the pressure generated by the are is effective to force insulating liquid across the contact surface of one or both of the coacting contacts.

It is an object of my invention to provide an improved Huid-break circuit interrupter of the expulsion type which shall be ecient in operation and simple and rugged in .construction.

It is a further object of my invention to provide an improved expansion and separating chamber for the oil and gases ejected from the main oil chamber or casing of an expulsion type oil circuit breaker.

Another object of my invention is to provide an improved insulating mounting structure for a high tension, high capacity fluid break circuit interrupter of .the aforesaid type My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 is an elevational view, partly in section, of a circuit interrupter embodying. my invention and Fig. 2 is a fragmentary cross sectional view taken along the line 2-2 of Fig. 1.

The circuit interrupter illustrated in Fig. 1 comprises the relatively movable contacts 1 and 2 adapted to engage and disengage within an insulating liquid 3 contained within a sleeve-like cylindrical insulating casing 4. The casing 4 is partially closed by a plate 5 suitably mounted thereon at its lower end and is open at its other end and in communication with an expansion and separating chamber 6. The chamber 6 is mounted upon an annular conducting member 7 to which the upper part of the casing 4 is suitably secured and has mounted at its lower part a spider, or the like, 8 providing the mounting structure for the stationary Contact 1. The openings in the spider 8 accordingly permit expulsion of the oil or other insulating liquid together with as past the stationary contact and into te eX ansion chamber where the gas is separated om the liquid and may exhaust by way of the vent 9 through the 1930. Serial No. 466,641.

pebble separating chamber 10. Accordingly the oil or other insulating liquid is not lost and flows by gravity back into the easing 4.

`The expansion chamber 6 may likewise be provided with an emergency exhaust vent 6o such as the concavo-convex disc 11 adapted to be blown through the opening 12 at the upper part of the casing in response t0 excessive pressure therein.

The stationary contact 1 ismounted adjacent the upper end of the casing 4 and comprises a cylindrical retaining structure 13 integrally secured to the spider 8 and a vertically movable contact member 14 provided with a stop shoulder l5 and normally biased, as by a spring 15', to the lower position illustrated in Fig. 1. The Contact member 14 is circumferentially engaged by a plurality of spring pressed Contact segments 16 electrically connecting the contact member to the contact retainer which is in turn electrically connected through the member 7 to one of the switch terminals 17.

The'movable contact 2 comprises a rod-like member having a blunt or rounded end adapted to make contact with the correspondingly shaped contact surface at the lower end of the Contact member 14 of the stationary contact 1. In the upper closed circuit position of the contact rod, it is engaged by the contact segments 16, the contacting surfaces being below the oil level.

For the purposes of guiding and operating the movable contact rod for vertical-movement within the casing, there is provided a guide member 18 and a rack and pinion operator 19-20 as best illustrated in Fig. 2. lThe guide 18 likewise makes sliding electrical Contact with the contact rod 2 and is mounted transversely of and in conducting relation with a depending housing 21 having a lower extension for the contact rod and provided with a terminal member 21. The pinion 20 is secured to a shaft 22 suitably journalled in the casing 21 through a fluid-tight seal 22 100 and is operatively connected to its actuating means (not shown) through an insulating conduit 23.

The insulating and mounting structure for the breaker comprises a pair of hollow insulat- 105 ing members 24 and 25 between which is disposed a xed support 26 having a central opening in registry with the insulating members, and in abutting engagement therewith. The support 26 is mounted upon a pair of 11o n casing 4 vwith respect to the supporting insulating structure so that only compression stresses are set up in the comparatively brittle insulating material, the casing 4 is provided with means hereinafter described for engaging the opposite outer ends of the insulating structure.l rIhe cylindrical casing 4 1 s also provided with an inner insulating lining 29 of materialhighly resistant to arcing and insulating spacers 30 are disposed between the lining 29 and the casing 4 to preventfracture of the lining by internal pressure. Secured to the upper end of the casing 4 is a flange 31 forming part of the member 7 which is in abutting engagement with and resiliently mounted on, as by the yielding gasket 32, the upper part of the insulating member 24. 'Ihe lower part of the casing 4 has secured thereto the centering plate 5 upon which is mounted the guide cylinder 33 for the Contact rod. The plate 5 is also provided with an offset flange 34 abutting a spacing ring 35 at the lower part of the insulator 25. The outer ends of the insulators 24 and 25 have united thereto as by cement the annular flanged members 36 and 37 for clamping the spacing rings 35 in position, the member 37 having bolted or otherwise secured thereto the depending housing 21- for closing and sealing the lower part of the casing 4.

The inner casing 4 and its associated elements comprise a unit having a resilient mounting with respect to the outer insulating structure which is mounted between the meinber 7 and plate 5. It will be noted, therefore, that the casing 4, regardless of the direction of the reactive -force during the current interruption, can transmit only compressive forces to the supporting insulators 24 and 25. For example, if the casing 4 is' subjected to a downward force during expulsion of oil therefrom, the insulator 24 is placed under compression whereas insulator 25 is under no stress since it is merely in abutting relation with the spacing ring 35. The insulators are, therefore, not subjected to tension and are less liable to failure. The insulating casing 4 may likewise be provided with reenforcing bands l38 at its opposite ends so that the casing, which issubJect to expansive forces and is under hoop tension, may safely withstand the forces generated by the arc. An annular space 39 separates the cas- When the circuit breaker is to be actuated from the open circuit position illustrated in Ifig. l to the closed circuit position, the pinion 20 is rotated by its actuating means to cause upward movement of the contact rod 2 through the oil and into abuttingy engagement with the lower end of the contact member 14. The operating rod overtravels its initial engagement so as to contact with the contact segments 16 and compress the spring 15 thereby obtaining good contacting engagement. The switch opening operation is effected by rotating the pinion 20 in the opposite direction and rapidly moving the contact rod downwardly out of engagement with the fixed contact and through the oil. 'Ihe following engagement of the member 14 during the initial part of the opening movement causes the arc to be formed between the separating contacts at the tip or blunt end of the contact rod and the coacting end of the member 14, and possibly at the lower portion of theretainer 13, thereby limiting the arcing to surfaces not normally carrying the main current.

The intense heat of an arc drawn within an insulating liquid such as oil, generates, as is well known, quantities yof gases at a high rate so as to greatly increase the immediate pressure. In the present instance, the formation of the arc tends to blast or expel the oil and gas at high velocity from the upper part of the casing 4 due to the sleeve-like proportions thereof, past the Contact 1 and upwardly into the expansion chamber 6 where the gas is partly cooled by passage through the pebble separating chamber l0 and exhausted exteriorly of the chamber by way of vent 9. 'Ihe oil, separated from the gas and remaining within the chamber, may thereafter flow back into the casing 4. As the Contact rod continues to move down- -wardly within the oil it is covered by fresh dielectric which tends to cool the arc at that point. In the event 4that the circuitis not at once cleared, continuation and lengthening of the arc as the contact rod moves downwardly, causes more oil to be expelled from the casing past and across the arcing surfaces of the contact 1 and into the expansion chamber so'as to carry away the arc products and to extlnguish the arc. In certain instances itA may be desirable to direct the ejected oil in a particular manner into th arc stream`4 or to increase the expulsion effect of the arc. For this purpose the casing 4 may be provided with insulating baffles-or barriers of well known construction arranged along the path of the arc.

It shall be understood that my invention is not limited to specific details of construclos tion and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without de arting from the spirit of my invent-ion.

Vhat I claim as new and desire to secure by Letters Patent in the United States is:

1. A circuit interrupter comprising` a pair of hollow insulating members, a fixed support for said interrupter intermediate and abutting said members, a cylindrical casing containing an insulating liquid disposed within and concentrically of said insulating members, and coacting contacts adapted to separate and draw an are within said insulatmg liquid, said casing includin means having abutting engagement with te opposite ends of said insulating members so that compressive forces only are transmitted to said insulating members during circuit interruption.

2. A high tension, high capacity circuit interrupter comprising a ollow insulating I structure, a fixed support for said interrupter 'frlgidly secured to sa1d` structure, a cylindrical casing containing insulating liquid disposed within and concentrically of said hollow insulating structure, and relatively movable contacts adapted to lseparate and draw an arc within said liquid, said cylindrical easing provided with flanged members at opposite ends thereof between which the corresponding ends of said insulating structure are mounted in abutting engagement so that said insulating structure is under compression between said casing and said fixed support due to explosive pressures generated within the casing uring circuit interruption. 3. An oil circuit breaker of the ex ulsion type comprising a vertically mounte cylindrical casmg containing oil, said casing beingr restricted in cross section as compared wit its length,y a stationary contact immersed in said oil disposed centrally of' and within the upper end of said casing, a rod contact coacting therewith and movable vertically through the oil within said casin g so that an arc drawn between said contacts within the oil is eiective to eject oil and the resulting arc gases through the arc and from the upper end of said casing, and an expansion and separating chamber disposed above and freely communicating with said casing for receiving oil and ases during circuit interruption, said cham er being provided with a separating chamber and vent for venting saidgases exteriorl of the chamber and permitting return of t e oil to said casing.

In witness whereof, I have hereunto set my 4hand this 7th day of July, 1930.

WILLIAM K. RANKIN. 

